Abrasive article



Patented Mar. 9, 1926 UNITED STATES,

PATENT OFFICE.

DUANE E. WEBSTER, 'OI' WORCESTER, MASSACHUSETTS. ASSIGNOB TO NORTON GOI-PANY, OF WORCESTER, MASSACHUSETTS, A CORPORATION OF MASSACHUSETTS.

No Drawing.

condensation product of formaldehyde andphenol which is soldon themarket under various trade names such as.bakelite, condensite andredmanol.

It is found that abrasive wheels made up I of such condensation products-of formaldehyde and phenol are notof sufli'cient hardness anddurability for certain cuttin pur poses, audit is accordingly the mam ob]8Ct of m invention to rovide a bond mixture w ich will give a arder andmore durable grinding body than may be obtiiiined by using suchsynthetic products a one.

In accordance with my invention, I pre pose to incor orate plaster ofParis in an abrasive artic e of this type, as I have discovered thatthis calcium sulphate has the remarkable property of combining-with thesynthetic condensation product of formalde-' hyde and phenol to form, avery durable and hard cement-like material WhlOh is well ada ted for themanufacturing of "grinding im ements. y

-s a specific illustration of one type' of abrasive article embodying myinvention, I may form a grindin wheel of a suitable abrasive, such ascry line alumina or sili' con carbide, combined with such thetic roductas is above described, and p aster of ans. While I may employ theplaster of Paris in proportions varying from ,6 to- 30%, I preferablyuse a mixture of 1D to 15% of plaster of Pans in order to obtain theharder grades of gun wheel. As a ifie illustration of one suitable comtion, I may employ (8% oi 'heat the abrasive material and then add thephenol-formaldehyde product and plaster of I claim as new and desire tosecure 7 anansrvn narrow. Application filed February 4, 1924. Serial.No. 890,862.

alumina grain, 15% of the phenol-formaldehyde condensation product and12% of plasterof Paris byweight. I

These materials may be combined and shaped into a grinding wheel bysuitable means and methods; As an example of one method which may beemployed, I prefer to Paris thereto and mix them in a suitable machine.When the mass has been suitably mixed I cool it and crush to a sizewhich is preferably slightly larger than that of the individual abrasivegrains, so that each grain will carry a small amount of bonding materialclinging thereto. Desired propore tions of these materials are weighedout and the mixture is then shaped in a mold of a. suitable form, afterwhich the mass is heated or baked at a temperature which will set orharden the bonding material. I prefer to heat the mixture'at about 320degrees F. for approximately ten hours. 7

In accordance with this invention I have provided an abrasive articlewhich is at least a ade. harder thanarticles made of a shellac 0nd orother similar materials, and I thereb enlarge the range of utilitywithin w ich articles of this type may be employed. A harder wheel ofthis type is more dense than one made without the laster of Paris.Because of its extreme ardnes's it has a much longer operating life thanheretofore obtainable and gives betterfinish on the work. I r Havingthus described my invention, what by Letters Patent is a 1. An abrasivearticle comprising granular abrasive material bonded by a condensationproduct of formaldehyde and phenol combined with plaster of Paris.

2. An abrasive article having abrasive grains united by a heat-set bondcomprisin a condensation product of 'formaldeh do an henol combined withplaster of Paris formmg from 30% by weight of the total mass.

Signed at Worcester, Massachusetts, this 29th day of January 1924.

DUANE E. WEBSTER.

